There is a need for reliable antibody tests for infectious diseases which are based on saliva and which are rapid, convenient, and inexpensive. Such tests would be especially valuable in work with IV drug abusers and prostitutes, where time spent with the patient is brief and follow-up is difficult. Use of saliva allows for a rapid "on the street" test since time precautions and equipment attendant with blood drawing and serum preparation are eliminated. The avoidance of needles makes the assay particularly valuable in testing prison populations. A rapid saliva-based test in the physician's office would also have great advantages. The proposed device utilizes a probe containing a microporous membrane and protein A to capture antibodies from a saliva sample or directly from the mouth and give a diagnostic result in l5 minutes. Having completed Phase I work demonstrating the sensitivity and specificity of the materials and principle of the proposed test, the investigators plan to build a device based on this principle and test it in clinical trials in support of an IND submission to the FDA. They propose clinical trials with their test for HIV-l antibodies and preclinical studies in development of tests for hepatitis A and hepatitis B.